Electric switch



March 5, 1957 0;;1. LUBBOCK m-AL 2,784,281

ELECTRIC SWITCH Filed Sept. 15, 1953 /NVE/vroRs OSW/L0 a. assoc/f EJAC/f Q. UBB

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ELECTRIC SWITCH Oswald Lubbock aud .lack 0. Lubbock, Alameda, Calif. Application September 15, 1953, Serial No. 380,234

Claims. (Cl. 20G-155) Our invention relates to switches for electrical circuits.

One of the objects of our invention is the provision of an electric switch in which simple parts moving toward and away from each other make or break the circuit without appreciable sound.

Another object is the provision of a switch in which arcing between make-and-break elements is substantially eliminated. A The invention possesses other objects and features of value, some of which, with the foregoing, will be set forth in the following description of our invention. It is to be understood that we do not limit ourselves to this disclosure of species of our invention, as we may adopt variant embodiments thereof within the scope 'of the claims.

Referring to the drawings: l Fig. 1 is a front elevation of the switch in the .position in which it is mounted in a switch outlet box. The

latter is shown in dash lines.

Fig. 2 is a vertical half sectional view taken in the plane indicated by the line 2 2 of Fig. 1. The switch is shown in the olf position; and a portion ofthe shaft is broken away to show the underlying structure.

Fig. 3 is a half sectional View showingthe relationship of the parts when the switch is in the on position. Again, a portion of the shaft is broken away'to'show the underlying structure. The plane of the section is indicated bythe line 3;'-3 of Fig. l.

Fig. 4 is a rear elevation of the casing cover plate, with the terminal plates, the bridge bar and carrier disc in assembled position, but removed from the rest ofthe structure. The View shows in full lines the relationship of the bridge-bar t'o the Vte'rr'tiiialV plates in oll position, and in dash lines the relationship in the on position.

Fig. 5 is a vertical half section of the parts shown in Fig. 4, taken in the plane indicated by the line 5--5 of Fig. 4.

Fig. 6 is a plan View of the casing with the drive arm or disc assembled therein.

Fig. 7 is a plan view of the spring which is interposed between the drive arm and bridge-bar.

Fig. 8 is a plan view of the bridge-bar, showing the way in which it is mounted on an insulating carrier disc.

Fig. 9 is a view similar to Fig. 4, but showing a rear elevation of the cover plate with only the terminal plates in place.

Broadly construed, we have provided an electric switch particularly suited for control of lighting circuits in the home; and in a slightly different embodiment, of special value in toasters, and other appliances in which the control switch is almost invariably the first part to break down. A simple element, moving through a short path in linear or arcuate motion with respect to a fixed element, creates an electrostatic or an ionized iield about the point of first contact, which then conducts the current across the narrowing gap until actual contact completes the metallic path. When the circuit is broken by Floe V,separating the contacts, the field conducts the current.

In bothiof' these cases the conducting path provided by the 'electrostatic or ionized field is either complete, or so nearly `complete, as to render what spark may occur invisible or inconsequential.

We do not fully understand all .phases of the phenomenon which .we have so clearly demonstrated-to exist by` many experiments, but we are persuaded that the absence of arcing in our switch is closely related to and dependent on these main factors: the creation of electrical capacity or an ionization between parts as they approach an engagement, and as they separate. Because of the simple and short movement` of the operating element, 'our switch is particularly adapted for use with a thermostat or other automatic control device of small power.

The switch of our invention as` designed for the control of lighting circuits in the home, comprising a casing on which are supported a plurality of spaced terminals for connection to the usual electric lead. Actuating mechanism within the casing, including a resiliently pressed bar, is arranged so as to bridge or break the gap between the terminals to make or break a circuit. A shaft journaled on the casing is operatively connected to the actuating mechanism within the casing, and means are provided for digital manipulation` of the shaft.

Specifically, the electric switch of our invention comprises a casing, preferably having a cylindrical sidewall 2, and a back end wall 3. It is closed at theopposite end by a removable cover plate 4. The case and cover areI preferably of molded non-conducting plastic and are secured together by screws 6 threaded into the side wall v2. The same screws secure the mounting bar 7 to the outside face of the casing for use in mounting the -switch on a junction box 8. As will be noted by inspection of the drawing, one of the screwsl 6 is shifted slightly off a diametrical plane passing through the axis 'of the other. This positioning permits the cover plate to be secured to the casein only one position.

The actuating mechanism of the switch is preferably contained within the hollow of the case; and includes an actuating shaft 12 journaled for rotation in the central bores 13 and 14 in the cover plate and end wall 3, respectively. A knurled knob 16 on one end of the shaft provides means for digital operation of the switch. A limit lug 17 adjacent .the opposite end of the shaft and adapted yto sweep back and forth within the limits imposed by the side walls`1`8 of the slot 19 in the end wall, provides means for limiting the rotation of the shaft.

Fixedly mounted on the shaft for rotation therewith is a drive arm 21, preferably a plastic disc of relatively heavy cross-section, provided with a radially spaced aperture 22, forming a socket for the stud 23 iixedly mounted on the bridge-bar 24.

The bridge-bar is preferably an arcuate strip of copper or brass, and is fixed on an insulating carrier disc 26 having a bore 27 through the center thereof large enough to permit a small wobble from a right angular position on the shaft. As shown best in Fig. 8, the bridge-bar and disc are secured together by the stud 23 and screw 25 so that their peripheries coincide. One end of the arcuate bridge-bar has a rounded edge 28 to facilitate riding up on the similarly rounded edge 29 of a terminal plate 31. It is this contact which closes the circuit when the knob 16 is turned clockwise; and at the time the disc 26 bearing the bridge-bar shifts its planar position as necessary to permit the bridge-bar to ride up into engagement with the terminal plate 31.

Two terminal plates 31 and 32 are provided. These are preferably of brass and each is fixed to the inside of the cover plate in a position diametrically opposed to the other. Each of the terminal plates includes an arcuate contact portion and a terminal lead portion 34, which extends outside the case and provides means to which may be connected the ends of an electrical lead.

As will be seen in Figs. 2, 3 and 5, the contact portion of terminal plate 32 is reduced in thickness so as to provide diterent levels for the two contact portions. In the assembly of the switch, the cover plate, carrying the two terminal plates, is secured to the casing `so that the .thin contact portion is engaged with the: arcuate bridgebar. A segmented disc spring 36, interposed between the drive-arm and the bridge-bar resiliently presses the bar against the reduced contact portion of the terminal plate 32. Thus, in the ot position of the switch, the bridge-bar is always lying dat against the contact portion of terminal plate 32. When the switch is turned to the on position, the leading rounded edge 28 of the bridgebar contacts and quickly rides up on the rounded edge 29 of the terminal plate, thus completing the circuit. The trailing end of the arcuate bridge-bar never loses contact with the contact portion of the plate 32, so that arcing at this contact is avoided.

Contact by the leading or rounded edge 28 is made silently since our switch is without snap action, and movement of the bridge-bar may be very slow. The approach or recession of the blunt or rounded bridge-bar relative to the terminal plate and its physical contact therewith or separation therefrom, is believed to have a material influence in preventing arcing across the gap as v it is closed or opened. As in conventional switches, the hot lead preferably passes through the switch, and in our switch is connected first to terminal plate 31, this plate then becoming the hot terminal.

We claim:

l. A silent switch for electric circuits comprising a casing, a shaft journaled in the casing, a plurality of terminal plates mounted in the casing, a bridge-bar, dielectric means for mounting the bridge-bar on the shaft, a drive disc concentrically mounted on the shaft for rotary movement therewith, means adjacent the periphery of the drive disc for loosely connecting it to the bridge-bar for effecting movement of the latter to make or break a circuit through the terminal plates, and a conical disc spring bearing against the drive disc adjacent its periphery and against the bridge-bar mounting adjacent the shaft for pressing the bar against the terminal plates.

2. A silent switch for electric circuits comprising a casing, a shaft journaled in the casing, a plurality of terminal plates mounted in the casing, a bridge-bar loosely mounted on the shaft, a drive disc fixed on the shaft, means connecting the disc and bridge-bar for eiecting movement of the latter to make or break a circuit through the terminal plates when the shaft is turned, and a segmented conical disc spring having its peripheral edge seated on the disc and its center portion bearing on the bridge-bar.

3. A silent switch for electric circuits comprising a casing, a shaft journaled in the casing, a plurality of terminal plates mounted in the casing, a disc loosely mounted on the shaft, a bridge-bar xed on the disc, a drive disc fixed on the shaft, means connecting the drive disc to the loosely mounted disc for rotary movement together, and spring means pressing the loosely mounted disc toward the terminal plates.

4. A silent switch for electric circuits comprising a casing, a shaft journaled in the casing, two spaced terminal plates arranged in the casing, a drive disc fixed on the shaft, a carrier disc loosely surrounding the shaft, means connecting the carrier disc for rotary movement with the drive disc, a bridge-bar Xed on the carrier disc,

va spring interposed between the shaft and the loose disc and pressing the bridgebar in a direction to slidably engage one of the terminal plates all of the time and the other terminal plate when the shaft is turned to close the circuit.

5. A silent switch for electric circuits comprising, a mounting plate, a closed casing including a cover and secured to the mounting plate with the cover next the plate, a shaft journaled in the cover and casing and extending through the mounting plate, an arcuate terminal plate concentric with the shaft and presenting a contact surface perpendicular to the shaft and fixed in the cover, a second arcuate terminal plate concentric with the shaft and presenting a contact surface perpendicular to the shaft and extending further than the first terminal plate into the casing, a dielectric disc on the shaft, a bridgebar mounted on the dielectric disc on one side of the shaft and between the dielectric disc and the terminal plates, a drive ldisc mounted on the shaft for rotation therewith and adjacent the end Wall of the casing, a stud xed to one of the dielectric disc or drive disc and loose in the other, and a spring pressing the bridge-bar against the first terminal plate continually and against the sccond terminal plate when the switch is closed.

References Cited in the file of this patent UNlTED STATES PATENTS 1,715,015 Soreng May 28, 1929 1,809,368 Winning June 9, 1931 2,041,414 Johnson May 19, 1936 2,440,690 Jacobi May 4, 1948 

